Sustained Whitening of Bleaching Strips: Results from Five Clinical Studies

The benefits of peroxide tooth whitening have been reported to last as long as 10 years. Objectives: This research evaluated the initial and sustained tooth whitening benefits of hydrogen peroxide self-applied whitening strips (manufactured by P&G). Methods: Whitening efficacy data from 5 separate clinical studies were analyzed to evaluate the initial and sustained benefit of 5.3% and 6.0% hydrogen peroxide strips. Maxillary teeth were treated for 30 minutes once or twice daily for 14 days. Efficacy (L*, a* and b* color change) was measured objectively by digital image analysis at the end of treatment and for up to 1 year post-treatment, with primary interest in yellowness reduction (Db*). Subjects were followed for 1 year in 2 studies and for 6 months in 3 studies. Paired sample t-tests (1 year studies) or regression analysis (6 month studies) were used to assess the significance of whitening benefit at 1 year post-treatment. Results: The end of treatment whitening benefit ranged from 1.6 to 2.6 Db* units. One year post-treatment the actual or predicted Db* ranged from 1.0 to 2.0 units. At the 1-year follow up visit, 65% to 81% of the initial whitening benefit was maintained (p < 0.05). Predictions based on regression analysis of 6 month studies indicate that 50% to 83% of the mean whitening benefit is maintained at 1 year. Conclusions: This research suggests the whitening benefit following various strip treatment regimens and hydrogen peroxide concentrations lasts at least a year.